[rkorchagin]

нашёл: http://msdn.microsoft.com/en-us/library/aa609747.aspx

permissionSet =  new Set(Types::Class);
    //get file write permission for createFile
    permissionSet.add(new FileIoPermission(fileName,'w'));
    //get file read/write permission for getFileSize and closeHandle
    permissionSet.add(new FileIoPermission('','rw'));

    CodeAccessPermission::assertMultiple(permissionSet);